Large Container Vessels Research Articles

Fatigue Life Assessment in the Typical Structure of Large Container Vessels Based on Fracture Mechanics

Welding defects are known to cause crack propagation and reduce structural fatigue performance. Based on the Paris theory of fracture mechanics, research is conducted on evaluation methods for analyzing fatigue crack propagation by adopting random loads with long-term distribution that follows the Weibull distribution for the stress ranges of fatigue loads. This approach is combined with the corrective stress intensity factor (SIF) equation and the method for calculating the reference stress and failure criterion. A large container ship is selected for a simulation, and fatigue crack propagation analysis is conducted on typical critical locations. A detailed comparison of the forecasted fatigue life is carried out between fracture mechanics theory and the S-N curve. The results indicate that the fatigue life values obtained using the two methods are of the same magnitude. In general, for the welded structure, the fatigue life value obtained via the fracture mechanics method is shorter than that obtained via the S-N curve method, while, for the free edge of the structure and the unwelded structure, the predicted fatigue life value is closer than that predicted via the S-N curve method. Moreover, the influence of initial crack defects on the fatigue life is investigated, and the results show that the depth of the initial crack will greatly affect the fatigue life of the target ship in typical locations, but the influence of the shape ratio on the fatigue life is limited. Therefore, in the actual ship construction process, controlling the initial crack depth of components is effective for limiting crack propagation and improving fatigue life. The above conclusions and suggestions can serve as a reference for the structural design and fatigue life evaluation of large container ships.

Analysis of the Mooring Effects of Future Ultra-Large Container Vessels (ULCV) on Port Infrastructures

The size of container vessels is continuously growing, always exceeding expectations. Port authorities and terminals need to constantly adapt and face challenges related to maritime infrastructure, equipment, and operations, as these are the principal areas affected by the future Ultra Large Container Vessels (ULCVs). Maneuvring areas are at their limits, and mooring equipment is at an increased risk of being overloaded. This study aims to analyze the limitations that present mooring systems may face when ULCVs are subjected to wind and passing-ship forces exerted by a future ULCV and wind forces through Dynamic Mooring Analysis (DMA). A hypothetical and massive future ULCV with a capacity of 40,000 TEU is compared to the Emma Maersk, which is a present vessel that regularly calls at container terminals. The Emma Maersk, with its current mooring arrangement, experiences higher motion than future ULCVs, which experience higher forces but are also moored with more and stronger lines. This translates into considerably higher loads in the mooring system, potentially compromising safe mooring conditions at the terminal. Mitigating measures are proposed in the study to face these limitations. In addition, the study explores the potential of new and innovative mooring technologies, such as high-strength synthetic ropes and smart mooring systems, to address the challenges posed by ULCVs. A container terminal at the Port of Rotterdam, Europe’s largest sea port, has been analyzed as a case study. The terminal is located next to a busy fairway that leads to other container terminals, justifying the need to analyze both wind and passing-ship effects on moored ships.

Prioritizing management of high-risk routes and ports by vessel type to improve marine biosecurity efforts

The shipping industry constitutes the main vector of marine bioinvasions. Over 90,000 vessels world-wide create a highly complex shipping network that requires appropriate management tools. Here we characterized a novel vessel category, Ultra Large Container Vessels (ULCV), in terms of potential contribution to the dispersal of Non-Indigenous Species (NIS) in comparison to smaller vessels traveling similar routes. Such approach is essential for providing precise information-based risk analysis necessary to enforce biosecurity regulations and reduce the adverse global effects of marine NIS. We used Automatic Identification System (AIS) based websites to extract shipping data that will enable us to test for differences in two vessel behaviors linked to NIS dispersal: port visit durations and voyage sailing times. We then examined the geographic spread of ULCVs and small vessels, quantifying the accumulation of new port visits, countries, and ecoregions for each vessel category. Finally, Higher Order Network (HON) analysis revealed emergent patterns within shipping traffic, species flow, and invasion risk networks of these two categories. Compared to the smaller vessels, ULCVs spent significantly longer time in 20% of the ports and were more geographically constrained, with fewer port visits, countries, and regions. HON analysis revealed that the ULCV shipping species flow and invasion risk networks were more similar to each other than to those of the smaller vessels. However, HON port importance shifts were discernible for both vessel categories, with major shipping hubs not necessarily being major invasion hubs. Overall, compared to smaller vessels, ULCVs behave differently in ways that potentially increase biofouling risk, albeit in a smaller set of ports. Future studies using HON analysis of other dispersal vectors appears critical for prioritizing management of high-risk routes and ports.

Maritime fuels of the future: what is the impact of alternative fuels on the optimal economic speed of large container vessels

This study aims to determine the most appropriate alternative fuel technology to comply with possible different imposed emission regulations while ensuring optimal business performance. In this context, the most suitable alternative fuel technology minimizes the required freight rate while maximizing overall performance on technological, environmental, and other criteria. A decision support tool was developed combining the overall performance of alternative fuels based on technological, environmental, and other criteria via a simple multiattribute rating technique model with a financial model based on discounted cash flow analysis. In this model, also an optimization model is implemented to minimize the required freight rate by optimizing for economic vessel speed. This model provides quantified insights into the financial and operational effects of transitioning via either a 'market-based measure' regulatory scenario or an 'emission cap' scenario if current fuels do not reach the zero-emission targets in the future. Based on the analysis, it can be concluded that upgraded bio-oil, Fischer–Tropsch diesel and liquefied bio-methane can be considered the 'most promising' alternative maritime fuels of the future. Current fuels such as Heavy fuel oil and Liquified natural gas remain the 'most probable' to retain dominance without regulations. If there is a transition toward these alternative fuels, this will also lead to a shift toward lower sailing speeds.

Study on the Root Causes and Prevention of Coating Cracks in the Cargo Hold of a Product Carrier

Recently, shipyards have been booming in the product carrier (PC) market of the global shipbuilding industry. Due to the rising market conditions, orders for large container vessels and PCs are also steadily increasing. According to the industry, freight rates for LR tankers (70K) and MR tankers (50K) in the shipbuilding industry have rose to the highest level during the previous year. In order to secure the competitiveness of PCs, various core items are required, and Korean shipbuilders have been leading the market for a long time based on their knowledge of the design and production of low-fuel ships. In recent years, there have been frequent cases of coating cracks in the cargo hold after sea trial. All relevant rules presented by the classification so far are structural design, safety evaluation, and inspection standards, and coating cracks are considered a problem for coating makers. In other words, they must establish a standard coating measure agreed upon by all parties (owner, shipbuilder, and coating maker); therefore, solutions have been proposed by each shipping company. In this study, the causes of coating cracks occurring in the cargo hold of PCs during tank tests in sea trials were analyzed and measures to prevent them were studied. The main point of this study is assumed that coating crack are caused by mechanical load induced by structural behavior, and the numerical analysis methodology is newly introduced. Based on the results of the numerical analysis, it was confirmed that there is a high probability of coating cracks in the critical area where high stress occurs in the cargo hold. Therefore, the results obtained in this study will be useful to prevent coating cracks in future PC designs.

Shipping voyage simulation reveals abiotic barriers to marine bioinvasions.

The shipping industry is considered the main vector of introduction of marine non-indigenous species (NIS). NIS distributions are often a consequence of frequent trade activities that are affected by economic trends. A dominant trend in the shipping industry is the operation of Ultra Large Container Vessels (ULCV), which are over 395 m long and sail mostly on the East-Asia - northern-Europe route. Understanding the risk of NIS introduction by this emerging shipping category is needed for devising strategies for sustainable shipping. Here, we conducted a controlled simulation of key abiotic factors that determine marine bioinvasion success: temperature, salinity, and food availability along selected routes, under two treatments: ULCV and intermediate-size vessels. We tested the effect of each treatment and the varying environmental conditions on the survival of two invasive ascidians (Chordata, Ascidiacea). We used survival analysis methods to locate predictors of ascidian mortality; Environmental conditions at ports with high mortality were used to identify similar major ports on a global scale as potential abiotic barriers. The key factors in ascidian mortality varied between the two species, but for both species, the treatment and salinity were dominant predictors for survival. We identified Port Klang, Rotterdam, and Dammam as ports with high mortality and located several globally distributed major ports that present similar environmental conditions. Our results highlight the potential role of selected major ports as abiotic barriers to fouling organisms during ocean voyages. The tolerance of the tropical-origin Microcosmus exasperatus to the northern-Europe conditions, and of the temperate/sub-tropical origin Styela plicata, to high temperature conditions, point out the urgent need to modify international fouling regulations in view of global change. Further studies on the survival of fouling organisms during a cascade of changing environmental conditions will contribute to the advancement of science-based regulations to reduce the adverse effects of NIS.

The dynamics of value propositions through social media engagement in maritime transport networks: Maersk vs Mediterranean Shipping Company

PurposeThis study explores the levels of Facebook engagement of the two largest Europe-based shipping lines, Maersk and Mediterranean Shipping Company (MSC), to discover the marketing orientation of the topics advertised and to ascertain whether they tend to be about brand recognition, new transport services, or value propositions for stakeholders.Design/methodology/approachThe Facebook posts of Maersk and MSC were analysed using social media text mining and social network analysis (SNA); in- and out-degree centrality analysis was performed to determine the key terms in their posts. NetMiner software was used to collect the respective data on Maersk and MSC. The inquiry period was set between May 2020 and February 2021.FindingsThe results indicated a divergence in their post contents, with higher engagement and a wider, more active follower base for MSC than for Maersk. Maersk primarily posts about logistics services and supply chain solutions. MSC communicates about new and large container vessels. Both companies seek greater brand recognition and information sharing through social media.Originality/valueThese results can be used by the stakeholders to evaluate whether Maersk and MSC truly deliver on their respective value propositions communicated online through their social media engagement. It can also help Maersk and MSC gauge the level of effectiveness of their communication with stakeholders and modify their digital engagement strategy accordingly.

Contested estuary ontologies: The conflict over the fairway adaptation of the Elbe River, Germany

The ongoing fairway adaptation of the Elbe Estuary is one of the most contested infrastructure projects in Germany in recent years. After a 17-year, highly contested planning process, delayed by a number of court proceedings, the dredging works started in 2019. The dredging aimed to establish a depth of at least 17.40 m below mean sea level, permitting the port to handle larger container vessels independent of the tide. Environmental NGOs, fishers and the riverine municipalities claim that the dredging will lead to habitat destruction, terminate the fishery in the estuary, and that it violates the European Water Framework Directive. The conflict illustrates that knowledge production, political economy and power are closely intertwined and provides evidence that some planning conflicts go even deeper than this. They are ultimately rooted in different ‘estuary ontologies’, in the different ways in which nature is enacted, and in different imaginations of possible futures for the Elbe estuary and its riverine population. Based on qualitative interviews with the actors who are involved in, observe or fight against the intervention, and on a content analysis of press articles and webpages, we unravel the complex relations between political economy, knowledge production and the different performances of reality which characterize the ongoing conflict over the fairway adaptation. We relate competing narratives, knowledge claims and ontologies to the actors promoting and challenging the fairway adaptation. Finally, we identify multiple estuary realities, which are enacted by specific practices performed by fishers, port authorities and environmental NGOs.

Shaft Alignment Self-Diagnosis Using the Smart Bearing Sensor

A fully functional prototype sensor has been developed to provide new insights into vessel shaftline dynamics that introduces real time data collection and performance evaluation. The Smart Bearing Sensor was recently tested onboard a large container vessel and was shown to work with promising results. The sensor is based on strain gauge technology and has been shown to enable continuous measurement of the bearing reaction load through the strain induced onto the bearing housing by the shaft. Given the capability of continuous monitoring and recording of the bearing reaction load and shaft misalignment angle, the prototype sensor removes the need for jack-up tests for re-alignment purposes. It is envisaged that this system will allow for the earliest possible diagnosis of shaft alignment-related problems, such as bearing unloading, bearing overloading or excessive shaft-bearing misalignment. The prototype sensor could be incorporated into a marine condition monitoring system that provides a more timely warning against bearing failures, particularly when compared to bearing temperature sensor indications.

Efficiency, safety, and reliability analysis of turbocharging in a large container vessel

AbstractCommercial shipping is currently dominated by mega container vessels. The shipping industry has seen a 10‐fold increase in the size of containers over the last four decades. These vessels are propelled by large marine diesel engines, hereafter referred to as the main engine. The performance of the main engine is determined by its subsystems. An important part of the main engine is the turbocharging system, which contributes to its safety, efficiency, and reliability. In this study, the effectiveness and reliability of the turbocharging system are evaluated. The Australian Maritime College has a Kongsberg Engine Simulator that can produce a variety of malfunctions on a running engine's turbocharging system. Analyzing the results obtained from the simulator determines the efficiency of the turbochargers. The study will provide recommendations for improving the safety of the turbocharging system for better performance to be achieved by the turbochargers, leading to an improvement in the main engine's performance. Last, the reliability of the turbocharging system is evaluated quantitatively using a fault tree analysis and reliability block diagrams. This will enable an optimum maintenance strategy to be established to ensure the safe operation of the vessel.

상업 운항 중인 대형 컨테이너선의 항차 중 속력 시운전을 통한 선속-동력 특성 연구 Part I

This paper presents the analysis of the speed-power performance in the real sea using a large container vessel data provided as a test bed from a shipping company. To perform a speed trial of the vessel during a commercial voyage, the on-board measuring device and various operation data acquisition systems were mounted on the vessel for long-term performance monitoring and the voyage operated under the container loading condition close to the design draft was adopted. The content of this paper consists of Part I and Part II. Part I, such as this paper, contains the speed trial method and analysis results of the operating vessel. Part II contains the analysis of the speed-power characteristics change over time and before and after hull cleaning using operation data measured from the voyage operated under a condition similar to the speed trial.

A Study on Under Keel Clearance of Gadeok Channel for the Safety Passage of Mega Container Ship

The worldwide sizes of container ships are rapidly increasing. The container ship size in 2005, which was about 9,200 TEU has increased to 24,000 TEU in recent times. In addition to the increase in the sizes of the container ships, the arrivals/departures of large container vessels to/from Korea have also increased. Hence, the necessity for reviewing safe passage of such vessels is emphasized. In the present study, a 24,000 TEU container vessel was used as a model ship to calculate the under-keel clearance (UKC) at Gadeok Channel through which vessels must pass to arrive at Busan New Port, in accordance with the Korean Port and Fishing Port Design Standards and Commentary. In addition, the maximum allowable speed that meets UKC standards was calculated using various squat formulas, whose results were then compared with the current speed limit standards. The analysis results show that Busan New Port requires 10% marginal water depth, and the squat that meets this requirement is 0.95 m. Gadeok Channel requires 15% marginal water depth, and the squat that meets this requirement is 1.78 m; in this case, the maximum allowable speed is calculated as 15 kts. Busan New Port has set the speed limit as 12 kts, which is higher than the calculated 11 kts. Thus, speed limit reconsideration is required in terms of safety. However, the set speed limit for Gadeok Channel is 12 kts, which is lower than the calculated 15 kts. Thus, additional considerations may be provided to increase the speed limits for smooth navigational passage of vessels. The present study, however, is constrained by the fact that it reflects only a limited number of elements in the UKC and allowable speed calculations; therefore, more accurate UKC and safe speed values can be suggested based on extended studies to this research.

Постановка и решение задачи проектирования рамного набора поперечной водонепроницаемой переборки крупнотоннажного контейнеровоза с использованием оптимизационно - поисковых процедур и нормативных требований правил DNV-GL

Поперечные переборки крупнотоннажных контейнерных судов представляют собой сложные конструкции, при проектировании которых обычно используется методология проверочного расчета на основе метода конечных элементов (МКЭ). Для создания конечно-элементной модели необходимо знать размеры всех элементов конструкций, входящих в состав переборки. Поэтому такой подход к проектированию является итерационным, что обуславливает высокую трудоемкость процесса проектирования. На ранних стадиях проектирования размеры конструкций поперечных переборок контейнеровоза могут быть быстро и достаточно точно оценены на основе аппарата нелинейного программирования, относительно простой модели составной (конструктивно-ортотропной) пластины и нормативных требований Правил классификационных обществ. Такой подход применяется в Российской практике при проектировании двойных конструкций типа двойное дно или понтон плавучего дока. В статье предложено решение задачи проектирования рамного набора поперечной переборки крупнотоннажного контейнеровоза на нагрузки от контейнеров, действующие на переборку при качке судна. Конструкция переборки приводится к условной модели «коффердамного» типа. Затем используется методика приведения составной «конструктивно-ортотропной» пластины к изотропной пластине с несколько иным соотношением сторон, но с такими же параметрами изгиба. Это позволяет применить существующие табличные данные для определения расчетных изгибающих моментов и перерезывающих сил, которые после аппроксимации представляются в виде полиномов – аналитических зависимостей. Показана постановка оптимизационно-поисковой задачи математического программирования. Целевая функция – характеристика массы рамного набора. Ограничения задачи формируются на основе нормативных требований DNV-GL и математических зависимостей модели составной пластины. Для решения задачи используется инструмент MS Excel «Поиск решения» Представлены результаты тестового проектного расчета применительно к конструкции крупнотоннажного контейнеровоз с контейнерной вместимостью 18 тыс. TEU. Сопоставление результатов проектирования с оригинальными расчетами фирмы – проектанта показали удовлетворительное соответствие. The transverse bulkheads of the large container vessels are complex structures that are commonly designed using the finite element method (FEM) verification methodology. To create a finite element model, it is necessary to know the dimensions of all structural elements of the bulkhead. Therefore, this approach to design is iterative, which leads to a high complexity of the design process. At the early stages of design, the dimensions of the structures of the transverse bulkheads of a container vessel can be quickly and accurately estimated based on the nonlinear programming technique, a relatively simple model of a composite (structural-orthotropic) plate, and the regulatory requirements of the Rules of Classification Societies. This approach is used in practice in Russia when designing double structures such as a double bottom or pontoon of a floating dock. The article proposes a solution to the problem of the transverse bulkhead web frames designing in application to a large-tonnage container vessel for loads of containers acting on the bulkhead when the vessel is moving on the waves. The bulkhead structure is reduced to the conditional "cofferdam" type model. The technique is used to reduce a composite "structurally-orthotropic" plate to an isotropic one with a slightly different aspect ratio, but with the same bending parameters. This allows applying the existing tabular data to determine the design bending moments and shear forces, which, after approximation, are represented as polynomial analytical dependencies. The statement the optimization-search problem of mathematical programming is shown. The goal function is the characteristic of the bulkhead's webs mass. The constraints of the problem are formed on the DNV-GL regulatory requirements and mathematical relationships of the composite plate model. MS Excel tool "Solver" is used to solve the problem. The results of a test calculation are presented as applied to a large-capacity container ship with container capacity of 18000 TEU. Comparison of the design results with the original calculations of the designer’s company showed satisfactory agreement.

Techno-economic assessment of advanced fuels and propulsion systems in future fossil-free ships

This paper analyses the potential of renewable fuels in different propulsion systems for the maritime sector that can replace fossil fuels by 2030. First, a fuel cost analysis is performed for a range of biofuels, bio-electrofuels, electrofuels plus liquid hydrogen and electricity in 18 fuel production pathways. Next, fuel production costs are combined with different utilisation rates, propulsion cost, on-board fuel storage cost and a cost for reduced cargo space to determine the total cost of ownership for four types of ships: large ferries, general cargo, bulk carriers and container vessels using internal combustion engines, fuel cells or battery-electric propulsion systems and travelling different distances.In large ferries, the battery-electric propulsion is found at a lower cost than all fuel options except biofuels. For the other ship types, cheaper fuels (as biofuels) benefit internal combustion engines, while expensive fuels (as electrofuels) increase the competitiveness of fuel cells due to their higher efficiency. Similarly, low utilisation rates benefit internal combustion engines, while higher utilisation rates tend to support fuel cells. General cargo vessels have a similar total cost of ownership for both four-stroke internal combustion engines and fuel cells. Bulk carriers and container ships use two-stroke engines, with efficiencies closer to fuel cells, but the lowest-cost solution remains internal combustion engines, except when increasing the efficiency or reducing the investment cost of fuel cells. In almost all fuel-propulsion combinations, methanol is the lowest-cost fuel, but dimethyl ether and ammonia show only marginally higher costs.

The emergence of very large container vessel (VLCV) in maritime trade: implications on the Malaysian seaport operations

Revolution in containerization has caused an impressive advancement in container shipping and significant developments have been witnessed in this industry, including infrastructure expansions, modern system design, technological advancement, emergence of multimodalism, and introduction of co-modality, as well as improvement in the mechanism of interoperability. Owing to a significant dynamism in maritime logistics, it is projected that the amplification of vessel capacity will continue and achieve up to 24,000 TEUs in coming years and even larger in order to cope with the demand of economies of scale (EOS). The increasing trend of throughput at container terminals to which the very large container vessels (VLCVs) have contributed has challenged seaport decision makers to carry out immense infrastructure improvements and make massive investments in current seaport terminals. Predicated on the previous issues, a question has been raised about the benefits and equality between seaports and liner shipping operators due to the emergence of VLCVs. As a result, this paper has identified, analyzed, and evaluated the impact of VLCVs on Malaysian seaport operations and infrastructures from the sustainability management perspectives. In order to achieve the research objectives, two mathematical methods are employed: the analytical hierarchical process and evidential reasoning. Three major seaports in Malaysia are selected, the Port of Tanjung Pelepas, Northport, and Westport, as case studies in this paper. The result obtained from this paper will assist seaport operators to develop their substantial strategies for adapting to the emergence of VLCVs.

Impact study of the fuel type used on the energy efficiency costs values and harmful emissions generation for small, medium and large container vessels

Annually a large amount of goods has been transported over the world and the most of the transportation is carried by seaborne. Although the seaborne trade is considered to be the most efficient – economically and environmentally friendly way of transportation an enormous amount of fossil fuels is used to fulfil the operation of the merchant fleet. Although we are living in times where efforts are directed to improvement of the state of the environment and reduction of the negative impact of the Greenhouse Gases, the fossil fuels still remain the main energy source used to run the internal combustion engines widely used in the ships nowadays. A well-known fact is that the fuel burning leads to significant harmful emissions generation causing a serious negative effect on the surrounding us environment. The introduced by IMO and MEPC requirements regarding the Greenhouse Gases (GHG) imposes for development and application of new criteria when selecting the ship’s propulsion plant. In the current article will be observed three ship groups consisting of real container vessels. The purpose is to analyse the impact caused by the fuel type used in the ship’s engines on the GHG generation and the economic indicators related with fuel costs

Influence evaluation of the ship propulsion system on the energy efficiency for small, medium and large container vessels

The transportation of goods worldwide has a vital meaning for the entire of humanity. The seaborne transport is considered to be the most efficient – economically and environmentally friendly way to convey large amount of goods when compared to the other transport options available. Marine vessels contribute for the carriage of about 90 percent of the worldwide trade and a significant part of the goods delivered by sea are performed by container vessels. Even considered as the most efficient way of transportation the negative aspects of the shipping should not be neglected. The fuels intended for the ship propulsion generating enormous amounts of Greenhouse gases (GHG) and harmful emissions which are directly released into the atmosphere. When it comes to Energy Efficiency of the ships, the proper selection of the propulsion system and the fuel type used are essential with regard to achieve the best values. In the current paper a diverse alternative propulsion system options in order to achieve maximum Energy Efficiency on various sizes of container vessels will be analyzed.

Constraint Programming and Local Search Heuristic: a Matheuristic Approach for Routing and Scheduling Feeder Vessels in Multi-terminal Ports

In the liner shipping business, shipping ports represent the main nodes in the maritime transportation network. These ports have a collection of terminals where container vessels can load and discharge containers. However, the logistics and planning of operations differ depending on the vessel size. Large container vessels visit a single terminal, whereas smaller container vessels, or feeder vessels, visit several terminals to transport all containers within the multiple terminals of the port. In this paper, we study the Port Scheduling Problem, the problem of scheduling the operations of feeder vessels in multi-terminal ports. The resulting problem can be identified as a version of the General Shop Scheduling Problem. We consider a Constraint Programming formulation of the problem, and we propose a matheuristic solution approach for solving large instances. The proposed matheuristic is a hybrid solution method that combines Constraint Programming with a local search heuristic. The solution approach benefits from the fast search capabilities of local search algorithms to explore the solution space using an Adaptive Large Neighbourhood Search heuristic. During the search, we further use the Constraint Programming model as an intensification technique, every time a new best-known solution is found. We conduct detailed computational experiments on the PortLib instances, showing that the incorporation of Constraint Programming within the heuristic search can result in significant benefits. The high instability in solution quality obtained by local search heuristics can be lowered by a simple combination of both methods.

A Study on the Influence of Large Container Vessels on Major Ports in Korea

본 연구에서는 이미 널리 인식되고 있는 선박 대형화가 실제 우리나라 주요항만에서 어떻게 어느 정도로 진행되고 있는가를 살펴보고자 한다. 부산항에만 국한하지 않고 주요 무역항으로 확대하여 그 추이의 정도를 비교해 보고자 주요 5개항으로 국한하였다. 또한 선종별 구분도 컨테이너선에만 국한하지 않고 수출입화물의 주종 품목을 감안하여 일반화물선, 산물선, 원유운반선, 석유정제품선, LPG·LNG운반선, 자동차운반선 등도 포함하여 이들의 추이 정도도 비교해 보고자 했다. 결론적으로 본 연구에서는 선박 대형화를 판단할 수 있는 지수나 지표의 개발이 어려운 이유를 밝히며 주요 항만별, 선종별 대형화 진행여부와 추이를 제시하였다. 이를 위하여 선박 대형화의 추이를 판정할 수 있는 이론적 방법론에 대하여 먼저 검토해 보고 적절한 방법론을 적용하여 그 실증분석을 수행하였다. 결과적으로 컨테이너선의 경우 모든 항만에서 선박 대형화가 진행되지 않고 부산항과 인천항에서만이 진행되고 있음을 보이고 있다. 인근지역 산업의 특성에 따라 평택항은 자동차운반선, 광양항과 울산항은 원유일반선, LPG·LNG운반선, 석유정제품선 등에서 선박 대형화를 확인할 수 있었다.

Wind modeling for large container vessels: A critical review of the calculation proce dure

With the increasing size of container ships, accurate methods to model manoeuvring and mooring conditions are indispensable. Especially in confined waters, where the ship speed is low or even zero, wind forces add a significant contribution to the force balance. The calculation of wind forces is typically done using wind coefficients based on wind tunnel tests. In these computations, a reference wind pressure must be used which is often based on the wind speed at 10 m height. When the wind blows over a rough surface however, the wind profiles become non-uniform, resulting in much higher wind speeds near the top of the ship, for the same wind speed at 10 m height. In case of differences between the wind profile used in the wind tunnel and the one expected in the reality, an appropriate reference pressure should be used. A method proposed by Blendermann to calculate such reference pressure is applied in this paper to a wind force calculation for an ULCS. It is shown that, depending on the roughness of the surface, the reference pressure can be a factor 2 to 3 higher than the one corresponding to 10 m height. This means that wind forces are potentially highly underestimated. The results of the method are compared with CFD simulations with a uniform and non-uniform inlet profile. The comparison shows a good agreement between Blendermann’s method and CFD results for the surge force and roll moment. On the other hand, Blendermann’s method seems to overestimate the sway force, but more simulations are needed before a firm conclusion can be drawn